Prospects for the use of antioxidant therapy in hypertension

The purpose of this review is to examine the indications and contraindications of antioxidant therapy in arterial hypertension. It has been suggested that oxidative stress plays a role in hypertension, increasing pressure values and leading to complications. Oxidative stress, at present, appears as one of several metabolic abnormalities described in essential hypertension. It is still uncertain whether this abnormality is primary or secondary; in any case, measurement of the main oxidant and antioxidant activities in plasma and blood cells may be useful in order to recognize and monitor oxidative stress. Antioxidant therapy could be useful to counteract the effects of oxidative stress on blood vessels, arterial pressure and low-density lipoproteins. Although antioxidant therapy with drugs or physiological substances in hypertensive subjects has been examined in some clinical trials, these experimental observations do not appear sufficient to draw definitive conclusions because long-term randomized, controlled studies do not exist. At present, it seems appropriate to propose some dietary recommendations which, apart from their antioxidant properties, are useful and do not have untoward effects. The safest approach to treat or to prevent oxidative stress consists of a diet that includes foods with a high antioxidant content (i.e. vitamins C and E and flavonoids). This diet consists fundamentally of fruits, vegetables and grains. Moreover it seems useful to use antihypertensive drugs that are able to decrease oxidative stress. The addition of physiologic antioxidant substances should be considered only in hypertensive subjects with a marked increase in oxidant or decrease in antioxidant factors. Indeed reactive oxygen species play a pivotal role in many physiological reactions, and their excessive inhibition could be dangerous. Further controlled, randomized long-term trials with antioxidants in hypertension are necessary to establish the efficacy and tolerability of antioxidants in the adjuvant therapy of hypertension.